<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <title></title>
    <style type="text/css">
        * {
            margin: 0;
            padding: 0;
            text-decoration: none;
        }
        body {
            padding: 20px;
        }
        #container {
            position: relative;
            width: 600px;
            height: 500px;
            border: 3px solid #333;
            overflow: hidden;
        }
        #list {
            position: absolute;
            z-index: 1;
            width: 4200px;
            height: 500px;
        }
        #list li {
            float: left;
            width: 600px !important;
            height: 500px  !important;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        #list li img {
            max-width: 100%;
        }
        #buttons {
            position: absolute;
            left: 250px;
            bottom: 20px;
            z-index: 2;
            height: 10px;
            width: 400px;
        }
        #buttons span {
            float: left;
            margin-right: 5px;
            width: 10px;
            height: 10px;
            border: 1px solid #fff;
            border-radius: 50%;
            background: #333;
            cursor: pointer;
        }
        #buttons .on {
            background: orangered;
        }
        .arrow {
            position: absolute;
            top: 180px;
            z-index: 2;
            display: none;
            width: 40px;
            height: 40px;
            font-size: 36px;
            font-weight: bold;
            line-height: 39px;
            text-align: center;
            color: #fff;
            background-color: RGBA(0, 0, 0, .3);
            cursor: pointer;
        }
        .arrow:hover {
            background-color: RGBA(0, 0, 0, .7);
        }
        #container:hover .arrow {
            display: block;
        }
        #prev {
            left: 20px;
        }
        #next {
            right: 20px;
        }
    </style>
</head>

<body>

<div id="container">
    <div id="list" style="left: 0px;">
    </div>
    <div id="buttons">
    </div>
    <a href="javascript:;" id="prev" class="arrow">&lt;</a>
    <a href="javascript:;" id="next" class="arrow">&gt;</a>
</div>
<script type="text/javascript">
    var data = window.location.href.split('?data=')[1];
    var list = data.split(',');
    var html = '';
    var htmlID = '';
    var count = 0;
    for(var i = 0; i < list.length; i ++){
        html = html + '<li><img src="/wissun-smfile/' + list[i] + '" alt=""/></li>';
        if(i == 0){
            htmlID = '<span index="' + (i + 1) + '" class="on"></span>'
        }else{
            htmlID = htmlID + '<span index="' + (i + 1) + '"></span>'
        }
        count++;
    }
    document.getElementById('list').innerHTML = html;
    document.getElementById('buttons').innerHTML = htmlID;
    /* 知识点：        */
    /*       this用法 */
    /*       DOM事件 */
    /*       定时器 */
    window.onload = function () {
        var container = document.getElementById('container');
        var list = document.getElementById('list');
        var buttons = document.getElementById('buttons').getElementsByTagName('span');
        var prev = document.getElementById('prev');
        var next = document.getElementById('next');
        var index = 1;
        var timer;
        var length = (count - 1) * -600;
        function animate(offset) {
            //获取的是style.left，是相对左边获取距离，所以第一张图后style.left都为负值，
            //且style.left获取的是字符串，需要用parseInt()取整转化为数字。
            var newLeft = parseInt(list.style.left) + offset;
            list.style.left = newLeft + 'px';
            //无限滚动判断
            if (newLeft > 0) {
                list.style.left = length + 'px';
            }
            if (newLeft < length) {
                list.style.left = 0 + 'px';
            }
        }
        function play() {
            //重复执行的定时器
            timer = setInterval(function () {
                next.onclick();
            }, 2000)
        }
        function stop() {
            clearInterval(timer);
        }
        function buttonsShow() {
            //将之前的小圆点的样式清除
            for (var i = 0; i < buttons.length; i++) {
                if (buttons[i].className == "on") {
                    buttons[i].className = "";
                }
            }
            //数组从0开始，故index需要-1
            buttons[index - 1].className = "on";
        }
        prev.onclick = function () {
            index -= 1;
            if (index < 1) {
                index = count;
            }
            buttonsShow();
            animate(600);
        };
        next.onclick = function () {
            //由于上边定时器的作用，index会一直递增下去，我们只有5个小圆点，所以需要做出判断
            index += 1;
            if (index > count) {
                index = 1
            }
            animate(-600);
            buttonsShow();
        };
        for (var i = 0; i < buttons.length; i++) {
            (function (i) {
                buttons[i].onclick = function () {
                    /*  这里获得鼠标移动到小圆点的位置，用this把index绑定到对象buttons[i]上，去谷歌this的用法  */
                    /*  由于这里的index是自定义属性，需要用到getAttribute()这个DOM2级方法，去获取自定义index的属性*/
                    var clickIndex = parseInt(this.getAttribute('index'));
                    var offset = 600 * (index - clickIndex); //这个index是当前图片停留时的index
                    animate(offset);
                    index = clickIndex; //存放鼠标点击后的位置，用于小圆点的正常显示
                    buttonsShow();
                }
            })(i)
        }
        container.onmouseover = stop;
        container.onmouseout = play;
        play();
    }
</script>

</body>

</html>

